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Wrong polarity from Generator


RufusR

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10 hours ago, nicknorman said:

The OP has a suitcase generator so the “chassis” is plastic. Apart from the exhaust outlet which it might be possible to touch if you really tried, I don’t think there is anything metal that could be touched.

 

But anyway, the generator earth is connected to boat hull via the lead, which as you say is a reasonable earth (depends on the water quality) so I’m not clear what additional safety having an earth spike would give for a metal framed genny.

 

I'm pretty sure the Honda EU range have metal chassis underneath the plastic cover. Every Honda suitcase generator I've ever owned has an earth stud connection point - and it's not connected to the plastic case! ?

 

You're probably better electrically informed than me, but if one is relying on the lead to earth the generator then the boat's own hull-earth bond must be in place and should be checked.

7 hours ago, ditchcrawler said:

I go along with that. No one ever suggested earthing your helicopters and they had generators or even if you have an inverter or travel power. the important thing is that your protection system works. It could be argued that no earth at all is safer in some circumstances. 

 

So what exactly is the chassis earth stud for on Honda EU generators?

 

I took advice from Gibbo and Chris W when I modified the generator lead and connected my generator earth stud to my hull.

Edited by blackrose
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13 minutes ago, blackrose said:

 

I'm pretty sure the Honda EU range have metal chassis underneath the plastic cover. Every Honda suitcase generator I've ever owned has an earth stud connection point - and it's not connected to the plastic case! ?

 

You're probably better electrically informed than me, but if one is relying on the lead to earth the generator then the boat's own hull-earth bond must be in place and should be checked.

 

So what exactly is the chassis earth stud for on Honda EU generators?

 

I took advice from Gibbo when I connected my generator earth stud to my hull.

You are confusing Earth like what earth rods are stuffed into and all mains electricity is tagged down to with a fault return line to the power source. You don't have an earth stake on your inverter but the fault return is via the "earth" wire to the inverter. Likewise when you plug into a shore supply you don't have an earth stake.  

Edit to add

As far as the earthing system on a Honda generator goes I don't have a clue so can't advise on the fault return to that.

Edited by ditchcrawler
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8 hours ago, ditchcrawler said:

You don't have an earth stake on your inverter but the fault return is via the "earth" wire to the inverter. Likewise when you plug into a shore supply you don't have an earth stake.  

 

 

Yes that's true about the inverter. But on the shore supply, whatever arrangement they have at the power station or distribution hub, I'd like to think it was a bit more sophisticated than an earth spike hammered into the ground? 

 

Anyway, confused or not, the case of my Honda EU30i generator is metal not plastic so I think I'm right in connecting the generator's earth stud to my hull.

Edited by blackrose
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1 hour ago, blackrose said:

 

Yes that's true about the inverter. But on the shore supply, whatever arrangement they have at the power station or distribution hub, I'd like to think it was a bit more sophisticated than an earth spike hammered into the ground? 

 

At the power supply end yes, but at your boat end its just a bit of wire in a three core flex. I think the only time I would put an earth stake in to the genny frame is where I had multiple appliances running on land but even then I don't think you would gain much, I can only think of is two concurrent cable damage incidents that could cause a problem and I am not even sure about that. Its something I would have to give a lot of thought to.

 

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1 hour ago, blackrose said:

 

Yes that's true about the inverter. But on the shore supply, whatever arrangement they have at the power station or distribution hub, I'd like to think it was a bit more sophisticated than an earth spike hammered into the ground? 

 

Anyway, confused or not, the case of my Honda EU30i generator is metal not plastic so I think I'm right in connecting the generator's earth stud to my hull.

 

The earthing arrangement for the mains is at the local HV transformer, and is either an earth rod, driven into the ground, or more likely several rods, joined together with copper barvto form an earth mat. It is checked so thst it has a resistance of 1 ohm or less.

 

Generators should be earthed, either to the earth connection of what they are supplying (boat hull, building earth etc), or in the absence of that (for example where the generator is supplying power at a tempory event held in a tent etc) to a local earth earth spike.

 

If the generstor is mounted ashore, and the cables are at risk of being damaged, then it would be prudent to use a  earth spike as well as the boats hull, so that the generator is earthed in the event of the earth cable being damaged, if only to mitigate your risk of electrocuting a passer by should a fault develop a d the earth cable become damaged.

 

The purpose is to provide a low resistance path to ensure correct and timely operation of fuses and circuit breakers.

Edited by cuthound
Clarification
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4 minutes ago, cuthound said:

The earthing arrangement for the mains is at the local HV transformer, and is either an earth rod, driven into the ground, or more likely several rods, joined together with copper barvto form an earth mat. It is checked so thst it has a resistance of 1 ohm or less.

 

On the farm (3-Phase) we had a big cable disappearing into the ground alongside the Cow-Shed with a label on it saying "PME System"

Never had any earthing problems

 

But, we don't appear to have PME on our 'new build' 3-phase supply.

 

Maybe its just an outdated system ?

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31 minutes ago, Alan de Enfield said:

 

On the farm (3-Phase) we had a big cable disappearing into the ground alongside the Cow-Shed with a label on it saying "PME System"

Never had any earthing problems

 

But, we don't appear to have PME on our 'new build' 3-phase supply.

 

Maybe its just an outdated system ?

 

No PME (protective multiple earth) is not outdated, in fact it is very common and still used. It is a variation on the TN-C-S system, but the neutral is bonded to earth at several points rather than just at the HV transformer.

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1 hour ago, cuthound said:

 

No PME (protective multiple earth) is not outdated, in fact it is very common and still used. It is a variation on the TN-C-S system, but the neutral is bonded to earth at several points rather than just at the HV transformer.

Like our cottage.

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Update got a qualified boat leccy to look today he ran tests etc . All it needs it seems is exactly what Nick said NE bonding . I asked about the fact this eu 2.0 and 2.2 were standard fair on the cut and he said that I was lucky I had a polarity indicator most didn’t hence they were merrily using these gens non The wiser .turns out EU in the title of this gen means Eu wiring which is opposite polarity to uk . Suppliers don’t care . 

 

It works unless you get a fault in which case the trips don’t work . Then again I expect many boats don’t have trips either . Maybe ignorance is bliss .

 

thanks for all the advice really helpful folks 

 

S

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Ok sorted am installing a earth bonded consumer unit near the gen. changing the gen inside invalidates the warranty according to Honda . I asked the leccy how come given these gens are popular fair on the cut there was not more problems to wit the answer was most boats don’t have polarity warning lamps like yours so they don’t know it could be dangerous . Bit worrying that ....

 

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6 hours ago, RufusR said:

Ok sorted am installing a earth bonded consumer unit near the gen. changing the gen inside invalidates the warranty according to Honda . I asked the leccy how come given these gens are popular fair on the cut there was not more problems to wit the answer was most boats don’t have polarity warning lamps like yours so they don’t know it could be dangerous . Bit worrying that ....

 

If you NE bond the consumer unit, when you plug into shore power and take some load, the bollard RCD will trip. This is why my advice was to do it within a lead made up for the purpose, not to be used with shore power. Of course if you are using a seperate connection/ consumer unit just for the genny, that will be fine.

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On 12/11/2019 at 23:27, ditchcrawler said:

Doing it in the generator, not in a lead that someone may use for something else

 

There are advantages and disadvantages to both. A modified cable could mistakenly be used for something else, but on the other hand a modified generator could be used inappropriately without the supply going through proper breakers (as if it still had a floating earth) leaving the user completely unprotected. 

 

Both modifications should be clearly labelled so that users know what they are doing. Even if you make the modification yourself and you're the only one using the generator it's easy to forget if you only use the generator infrequently.

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2 minutes ago, blackrose said:

 

There are advantages and disadvantages to both. A modified cable could mistakenly be used for something else, but on the other hand a modified generator could be used inappropriately without the supply going through proper breakers (as if it still had a floating earth) leaving the user completely unprotected. 

 

Both modifications should be clearly labelled so that users know what they are doing. Even if you make the modification yourself and you're the only one using the generator it's easy to forget if you only use the generator infrequently.

An important difference between those two scenarios is that the cable one carries zero safety risk - just a nuisance risk. Whereas the genny one does carry some safety risk, although fairly minor.

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On 17/11/2019 at 16:37, nicknorman said:

If you NE bond the consumer unit, when you plug into shore power and take some load, the bollard RCD will trip. This is why my advice was to do it within a lead made up for the purpose, not to be used with shore power. Of course if you are using a seperate connection/ consumer unit just for the genny, that will be fine.

The latter so no worries .

On 18/11/2019 at 17:57, blackrose said:

 

There are advantages and disadvantages to both. A modified cable could mistakenly be used for something else, but on the other hand a modified generator could be used inappropriately without the supply going through proper breakers (as if it still had a floating earth) leaving the user completely unprotected. 

 

Both modifications should be clearly labelled so that users know what they are doing. Even if you make the modification yourself and you're the only one using the generator it's easy to forget if you only use the generator infrequently.

FYI Honda said altering the gennie would invalidate the warranty.

On 19/11/2019 at 08:06, rupertbear said:

My Kippor generator has two outlets, directly paralleled internally. Rather than creating a permanent internal N-E bond or a bonded cable I use a 'dummy' trailing plug with the N-E bond within.

This is what we ended up doing 

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